cbcvebase.
CVE-2024-21733
published 2024-01-19

CVE-2024-21733: Generation of Error Message Containing Sensitive Information vulnerability in Apache Tomcat.This issue affects Apache Tomcat: from 8.5.7 through 8.5.63, from…

PriorityP334medium5.3CVSS 3.1
AVNACLPRNUINSUCLINAN
EPSS
14.29%
96.2th percentile
Generation of Error Message Containing Sensitive Information vulnerability in Apache Tomcat.This issue affects Apache Tomcat: from 8.5.7 through 8.5.63, from 9.0.0-M11 through 9.0.43. Other, EOL versions may also be affected. Users are recommended to upgrade to version 8.5.64 onwards or 9.0.44 onwards, which contain a fix for the issue.

Affected

7 ranges
VendorProductVersion rangeFixed in
apachetomcat
apachetomcat
apachetomcat>= 8.5.7 < 8.5.648.5.64
apachetomcat>= 9.0.1 < 9.0.449.0.44
apache_software_foundationapache_tomcat8.5.7 – 8.5.63
apache_software_foundationapache_tomcat9.0.0-M11 – 9.0.43
debiantomcat9< tomcat9 9.0.53-1 (bookworm)tomcat9 9.0.53-1 (bookworm)

Detection & IOCsextracted from sources · hover to see the quote

urlhttps://github.com/apache/tomcat/commit/86ccc43940861703c2be96a5f35384407522125a
urlhttps://github.com/apache/tomcat/commit/ce4b154e7b48f66bd98858626347747cd2514311
  • CVE-2024-21733 is a Client-Side Desync (CSD) / partial POST request smuggling vulnerability. Trigger condition: send a POST request with Content-Length: 6 but a body shorter than declared (e.g., a single byte 'X'). The server's error response for the incomplete request leaks body data from a prior user's request.
  • The vulnerability manifests as an HTTP 400 Bad Request error response that embeds data from a previous request in the 'Invalid character found in method name' error message — monitor for 400 responses from Tomcat whose body contains URL-encoded POST parameters from unrelated requests.
  • Incomplete POST requests triggered an error response that could contain data from a previous request from another user — detect by correlating POST requests with a declared Content-Length that exceeds the actual body bytes sent on a keep-alive connection.
  • Affected versions are Apache Tomcat 8.5.7–8.5.63 and 9.0.0-M11–9.0.43. Identify vulnerable servers via the version string disclosed in 404 error pages (default Tomcat error pages expose the version). Presence of these versions on internet-facing hosts should be treated as high-priority patching.
  • The exploit requires Connection: keep-alive and a mismatched Content-Length. Detection rule: flag HTTP POST requests where the Connection header is keep-alive, Content-Length is declared, and the actual body length is less than the declared value — especially when followed immediately by a 400 response on the same TCP connection.
  • The original vulnerability reporter is xer0dayz from Sn1perSecurity LLC; the canonical PoC is documented in HackerOne report #2327341. Threat intel pivot: monitor for tooling or scripts referencing this report ID.
  • ·The vulnerability only affects Apache Tomcat 8.5.7–8.5.63 and 9.0.0-M11–9.0.43. Red Hat Enterprise Linux ships unaffected versions and is not impacted.
  • ·Some public GitHub PoCs for this CVE are less reliable than the HackerOne report #2327341 payload; defenders should validate detection logic against the canonical payload rather than unreliable PoC variants.
  • ·The JSESSIONID cookie value found in victim.sh (EFC6BC3B39449C34A07AAEED1E9BE69A) is specific to the CTF challenge simulation and is NOT a real-world IOC; it was part of a poorly written simulation script acknowledged by the challenge author.
  • ·The keystore password 'yoyoma' and selfsigned.jks file are CTF-specific artifacts and not relevant to real-world exploitation of CVE-2024-21733.
  • ·Although CVSS scores this at 5.3 (Medium), the vulnerability can lead to authentication bypass by leaking credentials from other users' requests in a shared/multi-user environment.

CVSS provenance

nvdv3.15.3MEDIUMCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N
osv5.3MEDIUM
vendor_apache5.3MEDIUM
vendor_debian5.3MEDIUM
vendor_redhat5.3MEDIUM
vendor_ubuntu4.3MEDIUM
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